Coated articles are known in the art for use in window applications such as insulating glass (IG) window units, vehicle windows, and/or the like. Example non-limiting low-emissivity (low-E) coatings are illustrated and/or described in U.S. Pat. Nos. 6,723,211; 6,576,349; 6,447,891; 6,461,731; 3,682,528; 5,514,476; 5,425,861; and 2003/0150711, the disclosures of which are all hereby incorporated herein by reference.
In certain situations, designers of coated articles with low-E coatings often strive for a combination of high visible transmission, substantially neutral color, low emissivity (or emittance), low sheet resistance (Rs), and good durability. High visible transmission for example may permit coated articles to be more desirable in applications such as vehicle windshields or the like, whereas low-emissivity (low-E) and low sheet resistance (Rs) characteristics permit such coated articles to block significant amounts of IR radiation so as to reduce for example undesirable heating of vehicle or building interiors. It is often difficult to obtain high visible transmission and adequate solar control properties such as good IR blockage, combined with good durability (chemical and/or mechanical durability) because materials used to improve durability often cause undesirable drops in visible transmission and/or undesirable color shifts of the product upon heat treatment.
Low-E coatings typically include one or more IR reflecting layers. An IR reflecting layer is typically metallic or mostly metallic, and is often of a material such as silver (Ag), gold (Au), or the like. The silver or gold may be doped with other materials in certain instances. The purpose of the IR reflecting layer(s) is to block significant amounts of IR radiation, thereby preventing the same from undesirably heating up vehicle and/or building interiors which the coated article is protecting.
Generally speaking, the lower the electrical resistance (sheet resistance Rs and/or bulk resistance) of an IR reflecting layer, the better the IR reflecting characteristics thereof. However, it has heretofore been difficult to reduce resistance properties (and thus improve IR reflecting characteristics) of an IR reflecting layer without adversely affecting optical characteristics of a coated article (e.g., visible transmission, color, etc.) and/or durability of a coated article. For instance, significant changes in the thickness of an IR reflecting layer alone may affect resistance, but at the same time may adversely affect durability and/or optical characteristics of the coating.
In view of the above, it will be apparent to those skilled in the art that there exists an example need in the art for a technique for reducing resistance characteristics of an IR reflecting layer(s) thereby improving IR reflecting characteristics thereof and thus solar control properties of a coated article, without significantly adversely affecting durability and/or optical characteristics of the coated article. There also exists a need in the art for a method of making such a coated article.
In certain example embodiments of this invention, an infrared (IR) reflecting layer(s) is ion beam treated using at least ions from an inert gas such as argon (Ar) and/or Krypton (Kr). It has surprisingly been found that if the ion treatment is performed in a suitable manner, this causes (a) the electrical resistance of the IR reflecting layer to decrease compared to if the ion beam treatment was not performed, thereby improving IR reflecting characteristics thereof, (b) the emittance (e.g., normal) of the IR reflecting layer or coating to decrease compared to if the ion beam treatment was not performed, and/or (c) durability of the coated article to improve.
In certain example embodiments of this invention, it has unexpectedly been found that ion beam treatment of an IR reflecting layer of a material such as Ag, Au or the like, causes the stress of the layer to change from tensile to compressive. In this regard, it has been found that the compressive nature of the stress of the IR reflecting layer(s) can function to improve durability (chemical and/or mechanical) of the coated article.
Accordingly, suitable ion beam treating of an IR reflecting layer(s) has been found in certain example embodiments of this invention to achieve a combination of: (i) improved resistance of the IR reflecting layer, (ii) improved emittance, (iii) improved solar control characteristics of the coated article such as IR blocking, and/or (iii) improved durability of the coated article.
In certain example embodiments of this invention, the ion beam treating may be performed in a manner known as “peening.” In other words, the ion beam treatment of the IR reflecting layer may be performed after the IR reflecting layer has been originally sputter-deposited. After sputter-deposition of the IR reflecting layer in such instances, an ion beam comprising or consisting essentially of inert gas ions (e.g., Kr and/or Ar) is directed at the IR reflecting layer so as to impinge upon the same for ion beam treatment purposes. It has been found that this is advantageous for one or more of the reasons discussed above.
In other example embodiments of this invention, an IR reflecting layer may be formed in the following manner. First, a seed layer (e.g., of Ag or the like) is formed by sputtering. Then, after sputtering of the seed layer, ion beam assisted deposition (IBAD) is used to form an additional or remainder portion of the IR reflecting layer. In the IBAD type of ion beam treatment, both an ion beam source(s) and a sputtering target(s) are used. An ion beam from the ion beam source (e.g., including Ar+ ions) intersects with the material sputtered from the sputtering target(s) proximate the surface where the additional or remainder portion of the IR reflecting layer is being grown, so that the additional or remainder portion of the IR reflecting layer is grown/formed by a simultaneous combination of both the ion beam and sputtering.
In other example embodiments of this invention, the IR reflecting layer may be formed entirely using IBAD. At the beginning of the IR reflecting layer formation using IBAD, the volts applied to the ion source are low or zero so that the ion beam either is not formed or is of a low power type (i.e., low eV per ion). Then, during formation of the IR reflecting layer after at least some of the layer has been deposited, the voltage at the ion source is increased so as to increase the eV per ion in the ion beam. In other words, the ion energy is increased, either progressively or in a step-like manner, during formation of the IR reflecting layer. This prevents or reduces damages to the lower portion of the layer and/or to the layer under the same.
In certain example embodiments of this invention, a sputtering target(s) and an ion source(s) are located in the same deposition chamber so that they are at approximately the same pressure (e.g., at a pressure less than atmospheric pressure). In certain example embodiments, a lid of a deposition chamber supports both a sputtering target(s) (e.g., rotatable CMAG target) and at least one ion source. This permits sputtering and ion beam treatment to take place in the same deposition chamber at approximately the same pressure and/or gas atmosphere. Space can also be saved in this respect. The use of both a sputtering target(s) and an ion beam source(s) in the same chamber can be used in forming any suitable layer (e.g., Ag inclusive layer, or any other suitable type of layer) of various types of coatings on substrates. For purposes of example, and without limitation, such a structure with both an ion source(s) and a sputtering target(s) supported by the same lid of a deposition chamber, and/or both located in the same chamber at approximately the same pressure, can be used in any of the example embodiments discussed herein. For example, such a structure can be used in embodiments for peening an IR reflecting layer, in IBAD embodiments where the IR reflecting layer is formed using IBAD, and/or in embodiments involving a seed layer which is thereafter subjected to ion beam treatment discussed herein.
In certain example embodiments of this invention, there is provided a method of making a coated article, the method comprising providing a glass substrate; forming at least one dielectric layer on the substrate; providing at least one ion source and at least one sputtering target in a first deposition chamber; forming an infrared (IR) reflecting layer on the substrate over at least the first dielectric layer, where said forming of the IR reflecting layer comprises sputtering said sputtering target located in said first chamber and using an ion beam directed toward the substrate from said ion source located in said first chamber; and forming at least one additional dielectric layer on the substrate over at least the IR reflecting layer.
In other example embodiments of this invention, there is provided an apparatus for forming a coated article, the apparatus comprising a plurality of deposition chambers, including at least first, second and third chambers; a first sputtering target located in the first chamber; a second sputtering target and an ion source each located in the second chamber, wherein the second chamber may be at a different pressure and/or use a different gas atmosphere than the first chamber; and a third sputtering target located in the third chamber.
In certain example embodiments of this invention, there is provided a method of making a coated article, the method comprising: providing a glass substrate; forming at least one dielectric layer on the substrate; forming an infrared (IR) reflecting layer on the substrate over at least the first dielectric layer, where said forming of the IR reflecting layer comprises ion beam treating the IR reflecting layer; and forming at least one additional dielectric layer on the substrate over at least the IR reflecting layer.
In other example embodiments, there is provided a coated article including a glass substrates supporting a coating, wherein the coating comprises: at least one dielectric layer; an IR reflecting layer comprising Ag and/or Au provided on the substrate; at least one additional layer provided on the substrate over at least the IR reflecting layer; and wherein the IR reflecting layer comprises silver and has compressive stress and/or which is graded with respect to argon and/or krypton content.